SUZHOU, China—A Chinese woman who was critically injured while protecting a Japanese mother and child from a knife attack at a bus stop here has died, local authorities said on June 28.

Hu Youping, 54, was an assistant on a Japanese school bus when the attack occurred on June 24, Chinese authorities and other sources said.

A male assailant, 52, began attacking the Japanese mother and her preschool-age child with a knife as they were waiting at the bus stop, the sources said.

Hu stepped in to stop the attacker and was stabbed several times while trying to restrain him. She was sent to a hospital, where she died, the sources said.

The mother and child were also wounded, but their injuries are not life-threatening.

The city of Suzhou decided to award Hu a title recognizing her righteous and courageous actions.

If she had not intervened, the assailant could have entered the school bus and harmed more people, sources said.

The suspect has been detained. The motive for the attack is still unknown.